title: Fluorescence determination of D- and L-tryptophan concentrations in rat plasma following administration of tryptophan enantiomers using HPLC with pre-column derivatization.
abstract: Similar to L-tryptophan (L-Trp), D-Trp can be converted to unique metabolites in the mammalian body. In the present study, the difference in the plasma half-life (t(1/2)) between Trp enantiomers was investigated by following the alterations in the plasma concentration of D- or L-Trp after intraperitoneal (i.p.) administration of each enantiomer to male Sprague-Dawley rats (100 mg/kg). The investigation was performed using reversed-phase high-performance liquid chromatography (HPLC) and pre-column fluorescence derivatization with a chiral fluorescent labeling reagent, R(-)-4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N,N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole (R(-)-DBD-PyNCS). The t(1/2) value of D-Trp was significantly smaller than that of L-Trp, suggesting that D-Trp was eliminated from the plasma more rapidly than L-Trp. In addition, a significant increase in the plasma concentration of L-Trp was observed following administration of D-Trp, whereas no D-Trp was detected after L-Trp administration. Furthermore, the increase in the plasma concentration of L-Trp was significantly suppressed by pretreatment with an inhibitor of D-amino acid oxidase (DAAO), 3-methylpyrazole-5-carboxylic acid, which suggests that DAAO was involved in the conversion of D-Trp to L-Trp in vivo.
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-shi, Chiba 274-8510, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Iizuka
authors.forename: Kana
authors.initials: K
authors.lastname: Ishii
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hirasa
authors.forename: Kazumi
authors.initials: K
authors.lastname: Kubo
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fukushima
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013237:Stereoisomerism; D014364:Tryptophan / Q000097:blood* / Q000737:chemistry / Q000378:metabolism
chemical_list: D014364:Tryptophan